Overview of SPS in ERCOT

1. Overview of SPS in ERCOT February 5, 2004

2. Existing SPS • Current In-Service Special Protection Systems (SPS) on grid • Trip Hays generation to protect Kendall 345/138 kV Auto • Trip GPP & Rio Nogales generation to protect Marion to GPI 138 kV circuit • Trip DC Tie to protect for transient stability for close-in 345 kV faults • Trip DC Tie to protect Monticello-Sulphur Springs-Allen 345 kV circuits* • Trip LPP generation to protect Paris-Valley 345 kV & 138 kV circuits • Trip KPP & Valley generation to protect Valley-Anna & Valley Farmersville 345 kV circuits* • Trip Gateway generation to protect for transient instability • Trip Ennis generation to protect Ennis-Ennis West & Ennis West-Sterrett 138 kV circuits • Trip Parker-Roanoke 345 kV circuit to protect Roanake 345/138 kV auto • Trip Trent Wind Farm to protect Eskota Sw-South Abilene 138 kV circuit • Trip MELP generation to protect various circuits out of Venus & Everman includes remote monitoring of circuits and autos * To be modified in the Oncor proposal

3. Oncor NE CM Proposal • Modifies existing SPS with additional remote monitoring to automatically trip Valley & KPP in stages to protect several circuits • Modifies existing SPS with additional remote monitoring to automatically trip DC Tie to protect several circuits • Add SPS to automatically trip Valley #2 138 kV generation to protect both Valley-Payne 138 kV circuits • Add SPS to automatically trip breaker on Valley-Payne #2 138 kV circuit to protect Valley 345/138 kV autotransformer to minimize 345 kV generation tripping • Add SPS to automatically trip breaker on Collin-Bridges 138 kV circuit to protect this line • Add SPS to automatically trip breaker on E. Mesquite-W. Mesquite 138 kV circuit to protect this line

4. ERCOT SPS Requirements • Coordinated and approved with all affected parties • Use is limited to the time required to construct replacement transmission facilities, or replacement transmission facilities have been determined by ERCOT to be unnecessary (e.g., due to unacceptably high cost, inability to construct, or agreement by all affected parties). • Complies with all applicable ERCOT & NERC requirements • SPS must be fully automatic • SPS must not unnecessarily operate • The possible interaction of multiple SPS installations is considered • A methodology and medium for ERCOT Security Operations monitoring of the conditions that would actuate the SPS is provided. • It must be reviewed again whenever it is modified, after it has been in service more than five years, or whenever ERCOT believes system conditions merit its re-evaluation.

5. Additional Requirements Included in the NE SPS • Develop and install a “smart” monitoring and real time system including automatic oversight and data collection • Develop a comprehensive list of elements that could impact the SPS operation during outages/maintenance • Inspection of all critical facilities in May and November of each year for all SPS • Incorporate all SPS into TO and ERCOT System Operations, clearances coordination and TCR calculations • Misoperation will result in removal of SPS • Develop exit strategy • Perform probabilistic, steady state and dynamic studies of impacts of all SPS

6. NERC Planning Standards on SPS S1. An SPS shall be designed so that cascading transmission outages or system instability do not occur for failure of a single component of an SPS which would result in failure of the SPS to operate when required. S2. Misoperation, incorrect operation, or unintended operation of an SPS when considered by itself and not in combination with any other system contingency shall meet the system performance requirements as defined under Categories A, B, and C of Table I of the I.A. Standards on Transmission Systems. S3. All SPS installations shall be coordinated with other system protection and control schemes. S4. All SPS operations shall be analyzed for correctness and documented.

7. NERC Guides on SPS Guidelines define “Good Utility Practice” G1. Complete redundancy should be considered in the design of an SPS with diagnostic and self-check features to detect and alarm when essential components fail or critical functions are not operational. G2. No identifiable common mode events should result in the coincident failure of two or more SPS components. G3. An SPS should be designed to operate only for conditions that require specific protective or control actions. G4. As system conditions change, an SPS should be disarmed to the extent that its use is unnecessary. G5. SPSs should be designed to minimize the likelihood of personnel error, such as incorrect operation and inadvertent disabling. Test devices or switches should be used to eliminate the necessity for removing or disconnecting wires during testing.

8. Compliance ERCOT Measurements M1. Each Region whose members use or are planning to use SPSs shall have a documented Regional review process for SPSs to ensure that they comply with Regional criteria and guides and the NERC Planning Standards. M2. Each Region shall periodically review and document existing SPSs for compliance with the Regional planning criteria and guides and the NERC Planning Standards. TDSP Measurements M3. New or modified SPSs shall be reviewed for design and functional operation prior to being placed in service. The results of the compliance review shall be documented and provided to appropriate Regions and NERC upon request. (S1, S2) M4. The design and functional operation of an SPS shall be coordinated and reviewed with affected systems according to Regional compliance review processes. (S3) M5. Each Region shall have a process for the monitoring, notification, and analysis of all SPS operations. Documentation of SPS failures or misoperations shall be provided to the appropriate Regions and NERC on request. (S4) M6. Each SPS owner shall have an SPS maintenance and testing program. Documentation of the implementation of SPS maintenance and testing shall be provided to the appropriate Regions and NERC on request. (S1, S2)